New colonies and second-hand equipment can carry pathogens (foulbrood spores, Nosema, mites) undetected. A quarantine yard, kept physically separate from the established apiary, gives time to observe symptoms before merging.
P(spread to main yard) = base_risk(equipment) * (1 - sanitation) / (1 + distance/scale)
base_risk: used equipment > new colonies alone > new equipment
- Quarantine distance — physical separation from the main yard; the standard guidance is several kilometres for true isolation, modelled here on a simplified scale.
- Sanitization thoroughness — scorching/irradiating/replacing comb and boxes before reuse; directly cuts transmitted risk.
- New colonies — how many quarantined colonies are being observed at once.
- Used vs new equipment — used equipment carries meaningfully higher baseline risk (old comb can harbour American foulbrood spores for decades).
This mirrors real biosecurity guidance: distance and sanitation are the two levers that actually work, and neither alone is a substitute for the other.